Parkinson's disease is a chronic, progressive, neurologic disorder resulting from the selective degeneration of specific brain cells of the substantia nigra. These cells produce dopamine, a neurotransmitter which is necessary to communicate the neurochemical messages required for normal body movement and coordination.
The incidence of Parkinson's disease is reported as 1% of the population over the age of 50, and as high as 10% over the age of 65, with some occurrence in younger individuals but negligible incidence in children. Over half a million people in the United States are afflicted with this condition.
Clinical presentation of the disease includes tremors, muscular stiffness, slowness of movement and balance impairment. Walking difficulties may include shuffling, festination and akinetic episodes which are popularly referred to as "freezing." The course of Parkinson's disease and related extrapyramid disorders is variable but is usually characterized by a slow progression. The clinical manifestations of Parkinson's disease are divided into five stages from mild to severe, each stage reflecting the individual's capacity for functional ability. The hallmark of progression is when balance begins to deteriorate and the individual experiences complications of medical treatment.
Currently, medical treatment of Parkinson's disease is aimed at replacing the lost dopamine with a drug called Sinemet. The drug temporarily alleviates some of the symptoms for a few hours but does not cure the condition. While scientists continue to search for more effective medication and ultimately for a cure, the focus of everyday management is to prevent complications and assist individuals to manage the disease at home with emphasis on supporting their functional ability and in particular, their mobility. The ability to get around from place to place directly affects their quality of living.
The word akinesia means partial or complete loss of movement, and in the discussion of Parkinsonism usually denotes the sudden inability to initiate movement. Arms and hands may become momentarily akinetic, but much more commonly the feet/legs become akinetic. These "freezing" episodes present a distressing problem for the individual who is attempting to walk, by impairing their ability to get from place to place. The exact mechanism of pathology is not known; however, from a clinical standpoint, freezing episodes can correlate with low levodopa plasma levels or the Parkinsonian state. Freezing may also occur as a result of dopa-excess, as a side effect from the drug Sinemet, but this is rare.
The neurologist Joseph Jankovic M.D., in Clinical Neuropharmacology, Vol. 5, Suppl. 1, pg. S21, 1982, described freezing episodes thus:
"Some patients in more advanced stages of the disease develop sudden `freezing` episodes. One example of this is `start hesitation`, during which time the patient is unable to initiate gait or other movements. The freezing episodes may also be manifested by sudden interruption of mobility, particularly when walking through narrow passages or getting out of an elevator. Such freezing, termed akinesia paradoxica, may last from seconds to minutes and, occasionally, hours. It may be relieved by asking the patient to count `one, two, one, two, one, two,` by playing marching music, or by introducing sudden, unexpected, and even shocking situations, such as a tossed ball or the sudden loud noise of an approaching motor vehicle. This unexpected sudden mobility contrasts dramatically with the akinetic episodes described above and is termed kinesia paradoxica."
Usually, freezing is associated with the advanced stages of Parkinson's disease (stage 3,4,5) but it can also be present earlier in the disease course when balance is still intact. Individuals have described their feet as suddenly being "stuck", "glued" or "cemented" to the floor for brief (seconds) or longer (minutes) periods of time. This happens spontaneously while they are walking or as they begin walking (start-hesitation) with little warning. Some people are prone to freezing when they approach a narrow space, threshold or doorway. Freezing may occur once or several times in succession during a short walk, and the incidence of episodes may vary from day to day. Freezing and/or start-hesitation impedes free mobility and, as the disease progresses, increases the risk of falling.
People have attempted to manage these akinetic episodes in various ways. The scientific basis for the management techniques and why they work would be difficult to explain (even for a specializing neurologist), but they usually involve playing a "trick" on the brain; e.g., providing some visual cue which encourages the feet to step up and over, as if unsticking from glue, rather than stepping forward, as with regular walking. These tricks are usually taught in the physician's office by the doctors, nurses and therapists who are familiar with the symptom. People also learn the methods from reading books about Parkinson's disease or by attending support group meetings. One technique that some use is to march or rock to sound cues such as marching music or counting. Another method is to draw an imaginary line in front of the afflicted person's feet and encourage him or her to "step up and over the imaginary line." Also used is the dropping or placing of objects on the floor in front of the person's feet; forcing them to step over the object (paper, tissue, straws, belts, etc.). Virtually any object can be used to "step up and over."
The aforementioned interventions have been helpful to people, but each has drawbacks. Dropping or placing items of the floor requires not only that you have the objects ready to use but that someone be available to place and retrieve the objects. One alternative to this is to use small disposable objects (e.g., cards) and leave the object(s) behind. With other objects, if the object is 3-dimensional, such as a belt, the individual could trip and fall. The imaginary line method works well, but again, someone usually must accompany the individual to draw the line with their foot or hand. Some patients find it difficult to imagine a line during the freezing episode and remain unable to move until involuntary release occurs. Sound cues (such as marching music) are not often feasible, particularly outside the home, and many find singing or counting aloud embarrassing. Often, a Parkinsonian patient will just sit down and stop what he or she is doing. At the present time, these homemade tricks are the only mechanical techniques available to individuals in the United States who suffer from freezing and start-hesitation. For many people, the above-listed techniques are too impractical to consider using consistently.